Implement retainer



Nov. 29, 1938. E. H. DICKENSON IMPLEMENT RETAINER Filed April 50, 1938 INVENTOR. Erneaf flickenaon (ul-q llllll I 4 Y J, A 5

HIS ATTORNEY.

Patented Nov. 29, 1938 UN IT E D STATES;

PAT ENT' 9 FFI'TC'E,

IMPLEMENT RETAINER Application April 30,- 1938', Serial No. 205,193

4 Claims. I

retainer with a minimum of effort on the part of the operator.

Other objects will be in part obvious and in part pointed out hereinafter.

Inthe drawing accompanying this specification and in which similar reference numerals refer-to similarparts,

Figure 1 is a side elevation of a rock drill equipped with an implement retainer constructed in accordance with-the practice of the invention,

Figure 2 is an elevation, partly in section, of the front end of the rock drill and the retainer, and

Figure 3 is an elevation, in section, of the valve whereby the retainer may be controlled.

Referring more particularly to the drawing, the invention is shown applied to a rock drill comprising a cylinder 20 and front and back heads 2| and 22 which may be secured to the cylinder in any well known manner.

The rock drill is illustrated as being of the hand-held and guided type and has a handle 23 shown as being integral with the back head 22. The back head 22 also serves as a housing for a throttle valve 24 having a central chamber 25 which may be in constant communication with a source of pressure fluid supply through a conduit 26. The throttle valve 24 serves, among others, the well known function of controlling the admission of pressure fluid into the rock drill and is accordingly provided with a port 21 in its wall to afford communication between the chamber 25 and a supply passage 28 leading to distributing valve mechanism of which only the valve chest 29 is indicated in the rearward end of the cylinder 20.

The distributing valve mechanism may be of any suitable type for effecting the distribution of pressure fluid to the opposite ends of a piston 30 reciprocable in the cylinder 20 for actuating the working implement 3| arranged slidably in the front head 2 I.

The working implement 3| is illustrated as being in the form of a drill steel having a cutting bit 32 at its front end and a collar 33 at the juncture of the body portion 34 and the shank 35 to limit the distance which the shank 35 may extend into the front head. The collar 33 lies entirely within a bore 36 in the front head, and in the bore 36* is a bushing 31 'to receive the shank 35 and act as an abutmentfor the collar 33.

The steel retainer, constructed in accordance with thepractice of the invention and designated 38, is located at the front end of the front head 2| which, in order to accommodate the retainer 38, is provided with an enlargement 39 having a bore 49arranged, in the present instance, normal to thebore 36. The bore 40 comprises a series of stepped portions 4|; 42 and 43-which decrease progressivelyin diameter in the order named from the outer end of the bore which is sealed by a plug 44.

The retainer 38 is in the form of aplunger having a stem 45 which is slidably guided by the portion of the bore 43 and a head 46 in the portion-4|. Asa preferred arrangement, the retainer 38 is held against rotary movement with respect to the front head by a key 41, in the stem 45, slidable in a key slot 48 in the adjacent portion of the front head. On the free end of the stem 45 is a shoulder 49 which extends into the bore 36 and into the path of the collar 33 to act as an abutment for the collar.

The periphery of the head 46 slidably engages the wall of the portion 4| of the bore and the end of the head confronting the plug 44 constitutes a pressure surface 50 which is selectively subjected to pressure fluid for moving the retainer into and maintaining it in the retaining position. In the portion 42 of the bore 40 is a spring 5| that acts against the opposite side of the head 46 to shift the retainer into position for releasing the drill steel upon the exhaust of pressure fluid from the portion 4|.

The pressure fluid utilized for actuating the retainer 38 is conveyed into and from the bore 40 by a passage 52 leading, in the present instance, from the throttle valve 24 which has a partly annular groove 53 in its periphery to register with the passage 52, and a port 54 affords constant communication between the groove 53 and the chamber 25. The throttle valve 24 is further provided with a groove 55 arranged in the same transverse plane as the groove 53 to communicate the passage 52 with an exhaust port 56 leading from the chamber containing the throttle valve to the atmosphere.

The operation of the device is as follows: Whenever it is intended to begin a drilling operation the throttle valve 24 is rotated to communicate the chamber 25 with the passages 52 and 28. During the initial portion of the opening movement of the throttle valve the groove 53 is first brought into communication with the passage 52 so that pressure fluid will be introduced into the portion M of the bore to actuate the retainer to the retaining position prior to the admission of pressure fluid to the distributing valve mechanism.

The retainer will then be in position to prevent ejection of the working implement from the rock drill. The throttle valve 24 may then be further rotated in the same direction to bring the port 21 into registry with the passage 28 for supplying pressure fluid to the valve mechanism and, consequently, to the cylinder 20. The retainer will be held in the retaining position by the pressure fluid acting against the pressure surface 59 as long as the throttle valve occupies a position in which the: groove 53 registers with the passage 52.

Upon completion of a drilling operation the throttle valve is rotated to cut off the flow of pressure fluid to the distributing valve mechanism and. may, if desired, be placed in a position in which the groove 53 remains in registry with the passage 52. The retainer 33 will then remain in the retaining position and will prevent removal of the working implement during the time the rock drill is being shifted to a new drilling site.

Whenever it is intended to remove the working implement from the rock drill the throttle valve is rotated to a position in which the groove 55 registers with the passage 52 and. the port 56. The pressure fluid acting against the pressure surface 51! will then be exhausted to the atmosphere and the spring 5! will withdraw the retainer from the bore 36.

I claim:

1. An implement retainer for a percussive tool,

comprising in combination with a casing and a working implement, a retainer for the working implement movable in the casing and having a pressure surface, and a port in the casing to supply pressure fluid to the pressure surface for actuating the retainer with respect to the working implement.

2. An implement retainer for a percussive tool, comprising in combination with a casing and a working implement, a retainer for the working implement movable in the casing to retaining and releasing positions and having a pressure surface, a port in the casing to supply pressure fluid to the pressure surface for moving the retainer to one position, and a spring to move the retainer to the other position.

3. An implement retainer for a percussive tool, comprising in combination with a casing and working implement, a retainer for the working implement reciprocable in the casing and having a pressure surface, a port in the casing to supply pressure fluid to the pressure surface for moving the retainer into position to retain the working implement in the casing, and a spring to move the retainer into position to release the working implement.

4. An implement retainer for a percussive tool, comprising in combination with a casing and a working implement, a retainer for the working implement reciprocable in the casing, a head on the retainer, a pressure surface on one end of the head selectively subjected to pressure fluid for moving the retainer into position to retain the working implement in the casing, and a spring acting against the other end of the head to move the retainer into position to release the working implement.

ERNEST H. DICKENSON. 

